1. Field of the Invention
The invention relates to a memory device, and more particularly to an NAND flash with odd flag bits.
2. Description of the Related Art
In general, the data stored in an NAND flash may comprise main data and annotated data, wherein each annotated data is an auxiliary data of the main data. For example, the auxiliary data may be an error correction code or a memory cell failed symbol, wherein the auxiliary data is designed by its manufacturer according different practical applications.
After a wafer sorting process is performed, an NAND flash needs an additional redundancy circuit to replace a failed cell therein, so that the NAND flash may be operated normally. For example, Park (U.S. Pat. No. 5,694,359) discloses a Flash memory device, which has a repair circuit for replacing a failed cell of main memory cell arrays with a spare cell.
Compared with the main data, damaged auxiliary data also needs an additional redundancy circuit for repair even though the memory cells used by the auxiliary data occupies a minimal part of the total memory array.